“Thor” director Kenneth Branagh is walking away from Asgard, and no one is sadder than star Chris Hemsworth.

“I’m really disappointed,” Hemsworth said of Branagh’s decision to pass on “Thor 2,” which is aiming for a July 2013 release and may begin filming next May. “Ken built that character, and everything I know about the Thor world I learned while shoulder-to-shoulder with Ken. I learned so much from him.”

By all reports, Marvel Studios President Kevin Feige invited Branagh back to follow up his success of “Thor,” the May 6 release that has grossed $447 million in worldwide box office. The 50-year-old filmmaker seemed energized by the prospects of a sequel too, both in private and in public. In the end, though, the marathon devotion required for a major visual-effects epic and the urgency to get the script process underway were the factors that sent Branagh in a different direction. Instead of crossing the Rainbow Bridge again, Branagh will be busy as the returning star of the acclaimed British television series “Wallander” and with his ramping work with a theater group in his native Belfast.

Hemsworth, who visited Comic-Con International in San Diego this last weekend to promote “Snow White and the Huntsman,” said Marvel Studios will decide fairly soon on Branagh’s replacement. The 27-year-old actor has said the Oscar-nominated Branagh was initially intimidating and ultimately inspiring to work with, and that he has left a mark that will carry forward on the franchise.

“As long as he’s happy, that’s the thing,” said Hemsworth, who left San Diego to return to the New Mexico set of ”The Avengers.” “I learned so much from Ken while we built [the first film], so at least I had that time with someone like that. The start of anything creative is the most important period in a way. That’s when the most can go wrong, and Ken made sure we got it right.”